Ceramic-based light emitting diode (LED) devices, components, and methods

ABSTRACT

A light emitter device component containing one or more light emitter devices, such as light emitting diodes (LEDs) or LED chips, can include a body that can be ceramic and have a top surface, one or more light emitting devices mounted directly or indirectly on the top surface, and one or more electrical components mounted on the top surface and electrically coupled to the one or more light emitting devices. At least a portion of the top surface of the body to which the light emitting devices are mounted can be modified to have a reduced porosity compared to an as-fired ceramic body. Such components can result in improved adhesion strength and thermal management of the light emitting devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates and claims priority to U.S. Provisional PatentApplication Ser. No. 61/737,568, filed Dec. 14, 2012. This applicationis also a continuation-in-part of and claims priority to U.S. patentapplication Ser. No. 13/367,929, filed Feb. 7, 2012, and Ser. No.13/436,247, filed Mar. 30, 2012, the disclosures of which areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to components,modules, and methods for light emitting diode (LED) lighting. Moreparticularly, the subject matter disclosed herein relates to devices,components and methods for increasing brightness extracted from andimproving the manufacturability of light emitter devices, such as lightemitting diodes (LEDs) or LED components.

BACKGROUND

Light emitting diodes (LEDs) or LED chips are solid state devices thatconvert electrical energy into light. LED chips can be utilized in lightemitter components or packages for providing different colors andpatterns of light useful in various lighting and optoelectronicapplications. Light emitter components and methods can be used invarious LED light bulb and light fixture applications, and aredeveloping as replacements for incandescent, fluorescent, and metalhalide high-intensity discharge (HID) lighting applications.Conventional light emitter components can utilize one or more LED chipsmounted within a component body and sometimes surrounded by a reflectorcavity. A ceramic or ceramic-based substrate can be used in associationwith the one or more LED chips.

Despite the availability of various light emitter components in themarketplace, a need remains for improved LED devices, components andmethods.

SUMMARY

In accordance with this disclosure, light emitting diode (LED) devices,components, and methods are provided. It is, therefore, an object of thepresent disclosure to provide light emitter device components, modulesand methods improving adhesion strength and thermal efficiency of theLEDs.

These and other objects as can become apparent from the disclosureherein are achieved, at least in whole or in part, by the subject matterdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present subject matter includingthe best mode thereof to one of ordinary skill in the art is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures, in which:

FIGS. 1A and 1B are cross-sectional side views of a light emitter devicecomponent according to embodiments of the present subject matter;

FIG. 2A is a magnified image of a ceramic substrate with a substantiallyunmodified surface;

FIG. 2B is a magnified image of a ceramic substrate with a lappedsurface according to an embodiment of the present subject matter;

FIG. 2C is a magnified image of a ceramic substrate with a polishedsurface according to an embodiment of the present subject matter;

FIGS. 3A and 3B are cross-sectional side views of a light emitter devicecomponent according to further embodiments of the present subjectmatter;

FIG. 4 is a top view of a light emitter device component according tothe present subject matter;

FIG. 5 is a perspective view of a light emitter device componentaccording to the present subject matter; and

FIG. 6A is a cross-sectional view of a light emitter device componentalong line 6-6 of FIG. 4, and FIG. 6B illustrates a cross-sectional viewof another embodiment of the light emitter device component.

DETAILED DESCRIPTION

Reference will now be made in detail to possible aspects or embodimentsof the subject matter herein, one or more examples of which are shown inthe figures. Each example is provided to explain the subject matter andnot as a limitation. In fact, features illustrated or described as partof one embodiment can be used in another embodiment to yield still afurther embodiment. It is intended that the subject matter disclosed andenvisioned herein covers such modifications and variations.

As illustrated in the various figures, some sizes of structures orportions are exaggerated relative to other structures or portions forillustrative purposes and, thus, are provided to illustrate the generalstructures of the present subject matter. Furthermore, various aspectsof the present subject matter are described with reference to astructure or a portion being formed on other structures, portions, orboth. As will be appreciated by those of skill in the art, references toa structure being formed “on” or “above” another structure or portioncontemplates that additional structure, portion, or both may intervene.References to a structure or a portion being formed “on” anotherstructure or portion without an intervening structure or portion aredescribed herein as being formed “directly on” the structure or portion.Similarly, it will be understood that when an element is referred to asbeing “connected”, “attached”, or “coupled” to another element, it canbe directly connected, attached, or coupled to the other element, orintervening elements may be present. In contrast, when an element isreferred to as being “directly connected”, “directly attached”, or“directly coupled” to another element, no intervening elements arepresent.

Furthermore, relative terms such as “on”, “above”, “upper”, “top”,“lower”, or “bottom” are used herein to describe one structure's orportion's relationship to another structure or portion as illustrated inthe figures. It will be understood that relative terms such as “on”,“above”, “upper”, “top”, “lower” or “bottom” are intended to encompassdifferent orientations of the device in addition to the orientationdepicted in the figures. For example, if the device in the figures isturned over, structure or portion described as “above” other structuresor portions would now be oriented “below” the other structures orportions. Likewise, if devices in the figures are rotated along an axis,structure or portion described as “above”, other structures or portionswould now be oriented “next to” or “left of” the other structures orportions. Like numbers refer to like elements throughout.

Unless the absence of one or more elements is specifically recited, theterms “comprising,” “including,” and “having” as used herein should beinterpreted as open-ended terms that do not preclude the presence of oneor more elements.

Light emitters or light emitting devices according to embodimentsdescribed herein can comprise group III-V nitride (e.g., gallium nitride(GaN)) based light emitting diode (LED) chips or lasers that can befabricated on a growth substrate, for example, a silicon carbide (SiC)substrate, such as those devices manufactured and sold by Cree, Inc. ofDurham, North Carolina. Other growth substrates are also contemplatedherein, for example and not limited to sapphire, silicon (Si) and GaN.In one aspect, SiC substrates/layers can be 4H polytype silicon carbidesubstrates/layers. Other Sic candidate polytypes, such as 3C, 6H, and15R polytypes, however, can be used. Appropriate SiC substrates areavailable from Cree, Inc., of Durham, N.C., the assignee of the presentsubject matter, and the methods for producing such substrates are setforth in the scientific literature as well as in a number of commonlyassigned U.S. patents, including but not limited to U.S. Pat. No. Re.34,861; U.S. Pat. Nos. 4,946,547; and 5,200,022, the disclosures ofwhich are incorporated by reference herein in their entireties. Anyother suitable growth substrates are contemplated herein.

As used herein, the term “Group III nitride” refers to thosesemiconducting compounds formed between nitrogen and one or moreelements in Group III of the periodic table, usually aluminum (Al),gallium (Ga), and indium (In). The term also refers to binary, ternary,and quaternary compounds such as GaN, AlGaN and AlInGaN. The Group IIIelements can combine with nitrogen to form binary (e.g., GaN), ternary(e.g., AlGaN), and quaternary (e.g., AlInGaN) compounds. These compoundsmay have empirical formulas in which one mole of nitrogen is combinedwith a total of one mole of the Group III elements. Accordingly,formulas such as AlxGa1-xN where 1>x>0 are often used to describe thesecompounds. Techniques for epitaxial growth of Group III nitrides havebecome reasonably well developed and reported in the appropriatescientific literature.

Although various embodiments of LED chips disclosed herein comprise agrowth substrate, it will be understood by those skilled in the art thatthe crystalline epitaxial growth substrate on which the epitaxial layerscomprising an LED chip are grown can be removed, and the freestandingepitaxial layers can be mounted on a substitute carrier substrate orsubstrate which can have different thermal, electrical, structuraland/or optical characteristics than the original substrate. The subjectmatter described herein is not limited to structures having crystallineepitaxial growth substrates and can be used in connection withstructures in which the epitaxial layers have been removed from theiroriginal growth substrates and bonded to substitute carrier substrates.

Group III nitride based LEDs or LED chips according to some embodimentsof the present subject matter, for example, can be fabricated on growthsubstrates (e.g., Si, SiC, or sapphire substrates) to provide horizontaldevices (with at least two electrical contacts on a same side of the LEDchip). Moreover, the growth substrate can be maintained on the LED afterfabrication or removed (e.g., by etching, grinding, polishing, etc.).The growth substrate can be removed, for example, to reduce a thicknessof the resulting LED chip and/or to reduce a forward voltage through avertical LED chip. A horizontal device (with or without the growthsubstrate), for example, can be flip chip bonded (e.g., using solder) toa carrier substrate or printed circuit board (PCB), or wire bonded.Examples of horizontal LED chip structures are discussed by way ofexample in U.S. Publication No. 2008/0258130 to Bergmann et al. and inU.S. Publication No. 2006/0186418 to Edmond et al., the disclosures ofwhich are hereby incorporated by reference herein in their entireties.

One or more LED chips can be at least partially coated with one or morephosphors. The phosphors can absorb a portion of the LED chip light andemit a different wavelength of light such that the LED device or packageemits a combination of light from each of the LED chip and the phosphor.In one embodiment, the LED device or package emits what is perceived aswhite light resulting from a combination of light emission from the LEDchip and the phosphor. One or more LED chips can be coated andfabricated using many different methods, with one suitable method beingdescribed in U.S. patent application Ser. Nos. 11/656,759 and11/899,790, both entitled “Wafer Level Phosphor Coating Method andDevices Fabricated Utilizing Method”, and both of which are incorporatedherein by reference in their entireties. Other suitable methods forcoating one or more LED chips are described in U.S. patent applicationSer. No. 12/014,404 entitled “Phosphor Coating Systems and Methods forLight Emitting Structures and Packaged Light Emitting Diodes IncludingPhosphor Coating” and the continuation-in-part application U.S. patentapplication Ser. No. 12/717,048 entitled “Systems and Methods forApplication of Optical Materials to Optical Elements”, the disclosuresof which are hereby incorporated by reference herein in theirentireties. LED chips can also be coated using other methods suchelectrophoretic deposition (EPD), with a suitable EPD method describedin U.S. patent application Ser. No. 11/473,089 entitled “Close LoopElectrophoretic Deposition of Semiconductor Devices”, which is alsoincorporated herein by reference in its entirety. It is understood thatLED devices, systems, and methods according to the present subjectmatter can also have multiple LED chips of different colors, one or moreof which can be white emitting. As understood by those of skill in theart, an encapsulant can be used, such as by dispensing, in associationwith an LED component or substrate to cover one or more of the LEDchips. In this case, any suitable type and color of phosphor can beadded to the encapsulant in order to achieve desired light output of adesired color. This type use of phosphor can be instead of or inaddition to any phosphor coating of the one or more LED chips.

Embodiments of the present subject matter will be described withreference to FIGS. 1A-6B. Referring now to FIGS. 1A and 1B, a lightemitter device component can comprise light emitter device components orLED components that can be mounted over a substrate or body (e.g.,ceramic) without metal layers at the die attach interface. Generally, itis desirable for the substrate to be highly reflective to visible light(e.g., greater than about 90%) and provide conduction of heat andmechanical support. For example, ceramic materials containing aluminaare among the materials that contain these desirable qualities.

FIGS. 1A and 1B each illustrate a light emitter package or LEDcomponent, generally designated 110, mounted in this manner. LEDcomponent 110 as shown for example in FIG. 1A can comprise a substrateor body 112 that can be of any suitable material, such as ceramic, andcan be of any suitable shape and configuration. In comparison toconventional configurations for light emitter device components or LEDcomponents that use metal as a reflector (e.g., silver or aluminum), itis believed that ceramic-based LED components can provide improvedreflection and thus improved efficiency. Whereas metal reflectorsusually produce less than about 95% total reflection (i.e., diffuse plusspecular), ceramic-based substrates can have reflectivity beyond 95%.

To further improve the total reflection; at least portions of body 112can be designed to have increased porosity to further increase theamount of diffuse reflection. For example, desirable improvement inreflection can be achieved with open porosity of between approximately 0and approximately 15%. Those having skill in the art will recognize thatbody 112 can be configured to exhibit even higher values of porosity togive brighter results, but such additional improvements in brightnesscan come at a cost of mechanical stability and thermal performance. As aresult, designing body 112 to have a porosity in the range of betweenapproximately 0 to 15% can provide a good balance of these factors.Ceramic materials can further be desirable for use in LED componentsbecause of thermal management properties. For example, Alumina materials(AL₂O₃) have relatively low thermal resistance, low moisturesensitivity, superior reliability at high temperature environments, andthe superior ability to dissipate heat.

In one aspect, body 112 can comprise a ceramic body cast using lowtemperature co-fired ceramic (LTCC) materials and processes.Specifically, for example, body 112 can comprise a ceramic substratecast from a thin green ceramic tape. The ceramic tape can comprise anyceramic filler material known in the art, for example, glass ceramicssuch as aluminum oxide (Al₂O₃) or aluminum nitride (AlN) having 0.3 to0.5 weight percent of glass frits. The glass frits can be used as abinder and/or sintering inhibitor within the ceramic tape when the tapeis fired. A green tape can be formed by casting a thick layer of aslurry dispersion of the glass frit, ceramic filler, one or moreadditional binders, and a volatile solvent. The cast layer can be heatedat low temperatures to remove the volatile solvent. A green ceramic tapeused for body 112 can advantageously comprise any thickness desired,thus contributing to a thinner size when desired.

In another aspect, HTCC can be used. Body 112 can further comprise aceramic material having any of a variety of scattering particlecontained therein. Examples of suitable scattering particles can forexample comprise particles of Al₂O₃, TiO₂, BaSO₄, and/or AlN. In oneparticular embodiment, Al₂O₃ particles can be selected based on costconsiderations, along with its mechanical, optical, electrical, andthermal properties. In still another aspect, the substrate can be acomparatively simple structure without intervening layers such as thoseproduced by thin- or thick-film processes (e.g., bare substratesproduced CoorsTek and several others). Such substrates can be firedalong with other materials (e.g., Zirconia) to improve optical andmechanical properties. Body 112 can instead comprise any other suitablematerial or materials, and any suitable layer or portion, such as forexample a non-metallic layer, can be disposed on or over body 112.

Despite these advantages, however, as-fired ceramic materials generallyhave a surface that is porous and rough, such as is shown in FIG. 2A.Although this profile can provide good reflection properties asdiscussed above, those having skill in the art will recognize that thesecharacteristics are often not considered optimal for attaching an LEDdie. Specifically, for instance, both the adhesion strength and thethermal resistance can be affected. To address these issues, any of avariety of surface modifications can be used to improve the surfaceprofile of body 112 to receive LED component 114. First, for example,lapping, polishing, and/or other mechanical modification processes canbe applied to at least a portion or surface of body 112 to offer someimprovement by smoothing the contact surface to thereby increase thecontact area with LED component 114. For instance, FIG. 2B shows aceramic surface that has been modified by lapping, and FIG. 2C shows aceramic surface that has been modified by polishing. Regardless of thespecific mode by which the contact surface is smoothed, the increasedcontact area can thereby result both in greater adhesion strength andbetter thermal contact. Such mechanical processes can result incontaminants being trapped within the surface, however, which cannegatively affect the reflection properties of the surface.

Alternatively, a coating can be applied to the surface of body 112. Thecoating can be selected based on any of a variety of characteristics,such as good surface morphology or thermal conductance. The coating canpreferably be selected to improve thermal contact and adhesion withoutsignificantly reducing the reflection from the surface. Examples of acoating that can provide such improvement to the ceramic surface caninclude silicone, epoxy, or another polymer known to those having skillin the art. Alternatively, the coating can comprise a ceramic material.In addition, the coating can contain reflective particles therein, suchas alumina, titanium, dioxide, zirconia, or any other reflectiveparticle known to those having skill in the art. The coating can befired with a flux or without a flux (i.e., in a sintering process).Furthermore, once applied, the coating can itself be mechanicallymodified, such as by lapping, polishing, or other mechanicalmodification.

Regardless of how the surface profile of body 112 is smoothed, however,the result can be a surface that provides greater adhesion and betterthermal contact with LED component 114. Such a surface modification canbe provided only in particular regions of the surface of body 112, suchas at positions where LED component 114 will be attached as shown inFIG. 1A (i.e., the surface is modified at a die attach interface 117,but the remainder of the surface is comparatively rough), or the entireupper surface of body 112 can be modified as shown in FIG. 1B.Similarly, at least a portion of the surface that opposes the side towhich LED component 114 is attached (i.e., the “bottom” surface) canlikewise be lapped, polished, coated, or otherwise modified to improvethe thermal contact and/or adhesion strength for any components attachedthereto. Of course, it should be recognized that other combinations ofcomponent configurations and surface modifications beyond those shown inFIGS. 1A and 1B are within the scope of the present subject matter.

Referring again to FIGS. 1A and 1B, body 112 can for example be formedwith or without any cavity or recess so that one or more LED chips 114are disposed on and can mount to body 112. As one example, body 112 cancomprise a surface, such as an upper surface, that can but does not haveto be disposed along a single plane. The one or more LED chip(s) such asLED chip 114 can be mounted directly to the surface of body 112 withonly a thin adhesive layer (e.g., silicone or epoxy) between body 112and LED chip 114 (i.e., without any intervening layer, such as a metalor other layer, as shown for example in FIG. 1A). Alternatively, the oneor more LED chip(s) such as LED chip 114 can be mounted indirectly tothe surface of body 112 as shown for example in FIG. 1B where LED chip114 is mounted to a first intervening layer 116 that can be anon-metallic layer or a metallic layer. One or more than one interveninglayer can be used and all of them can be non-metallic layers. Forexample and without limitation, a second, intervening layer 118 can alsobe disposed between body 112 and LED chip 114 as shown in FIG. 1B wheresecond intervening layer 118 is below and against first interveninglayer 116. In particular, second intervening layer 118 can be a coatingof material that improves the thermal contact and the ability of LEDchip 114 and first intervening layer 116 to be adhered to body 112 asdiscussed above. The one or more intervening layer(s) can be of a widththat is identical to, less than or greater than the width of LED chip114. As an example, second intervening layer 118 is shown with a widththat is wider than that of LED chip 114, and arrows Al in FIG. 1Bindicate broken lines to illustrate where first intervening layer 116could extend to instead as one example where first intervening layer 116would have a width that is less that the width of LED chip 114.

In either arrangement, LED chip 114 can be electrically connected, suchas by wirebonds 120 or any other suitable technique, to one or moreelectrical components. As used herein, electrical components can, forexample and without limitation, comprise electrical traces, leads,electrical pads, contact or bond pads, or any other suitable electricalcomponent. For example, first and second electrical components 122 and124 can each comprise a copper foil having wire-bondable gold or silverportions provided thereon. One of the first and second electricalcomponents 122 and 124 can serve as a cathode and the other as an anodefor supplying LED chips 114 with current to illuminate an active layerwithin the LED chip. Alternatively, LED chip 114 may be flip-chip bondedto the first and second electrical components. Any other suitablebonding techniques could be used as well. Regardless of the specificconnection, first and second electrical components 122 and 124 can beseparated from body 112 by one or more non-metallic layers. Forinstance, as shown in FIGS. 1A and 1B, optionally adhesive layers 126and 128 can be positioned between body 112 and first and secondelectrical components 122 and 124, respectively. For example, adhesivelayers 126 and 128 can each comprise an organic-based adhesive, apressure-sensitive adhesive (PSA), and/or an epoxy, a Room TemperatureVulcanizing (RTV) silicone, or silicone adhesive.

By connecting LED chips 114 and first and second electrical components122 and 124 to body 112 using non-metallic layers (e.g., first andsecond intervening layers 116 and 118, adhesive layers 126 and 128), themanufacturability of LED component 110 can be greatly improved.Specifically, for example, prior art methods require resource-intensiveprocesses in which a seed layer is deposited on the substrate byphysical vapor deposition or the like, and copper is plated on the seedlayer to produce electrical traces on the substrate. Other metals aretypically plated on the copper to make them wire-bondable. Such methodscan require a number of additional processing steps with respect to body112, and these additional processing steps can leave contaminates on theceramic surface, which can be difficult to remove and can negativelyimpact the performance (e.g., brightness) and reliability of the device.In contrast, using one or more intervening non-metallic layers asdiscussed herein, first and second electrical components 122 and 124 canbe adhered to body 112 in a comparatively simpler process. In such aconfiguration, the trace pattern can be formed separate from substrate112 and applied using a lamination technique, such as for example a heatpress and/or an overpressure chamber (i.e., autoclave) laminationtechnique with an adhesive film known to those having skill in the artin the multi-layer printed circuit board industry.

Further in this regard, in an alternative configuration shown in FIG.3A, LED component 110 can comprise an additional dielectric layer 127positioned between body 112 and first electrical component 122.Likewise, although not shown in FIGS. 3A or 3B, a similar dielectriclayer can be positioned between body 112 and any other electricalcomponents (e.g., second electrical component 124). Dielectric layer 127can be any of a variety of material layers known in the art, such as acopper clad laminate (CCL) (e.g., glass-reinforced FR-4, CEM-3, CEM-4,or other related composite materials, such as CS-3965 from Risho). Inone particular embodiment, for example, dielectric layer 127 can be aflexible printed circuit board (“flextape” PCB) comprising apolymer-like film having at least one conductive layer within one ormore layers of a flexible plastic resin (e.g., polyimide, Kapton fromDuPont). In this exemplary configuration, adhesive layer 126 cancomprise a tape-like adhesive provided on the flextape for easyconnection to body 112. It should be recognized, however, thatdielectric layer 127 can comprise any material used in multilayer PCBsor flex PCBs, including prepreg materials, reinforced laminates (e.g.,glass-reinforced epoxy, materials using carbon fiber), andnon-reinforced materials.

As further illustrated in FIG. 3A, additional components can beintegrated into LED component 110 to improve the performance andmanufacturability thereof. For example, LED component 110 can furthercomprise an electrically insulating solder mask 130, which can bedisposed on dielectric layer 127 and at least partially on electricalcomponents 122 and 124 such that when solder is used to attach one ormore wires to an electrical solder pad (not shown), the solder will becontained within the predefined area. Choosing a white solder mask canimprove the overall reflectivity of LED component 110. Similarly, afillet 134 can be provided around a perimeter of a light emitting areadefined above the top surface of body 112, which can be eithertransparent or reflective (e.g., white). For example, fillet 134 can bemade white by incorporating TiO₂ particles therein or by forming fillet134 of silicone or epoxy materials. Regardless of the specificconfiguration, fillet 134 can improve reflection of the sidewallportions of LED component 110, thereby compensating in configurationswhere dielectric layer 127 has a comparatively lesser reflectivity(e.g., where dielectric layer 127 comprises FR-4). Exemplaryconfigurations for LED component 110 having such a fillet 134 can befound in commonly owned U.S. patent application Ser. No. 13/435,912,filed Mar. 30, 2012, the disclosure of which is incorporated byreference in its entirety herein.

LED component 110 can further comprise a retention material 132 disposedat least partially about an emission area in which LED chip 114 ispositioned, where retention material 132 can be referred to as a dam.After placement of retention material 132, an encapsulant E can bedisposed within the recess formed thereby. Encapsulant E can contain oneor more phosphors such that light emitted from the one or more LED chips114 can produce an emission with desired spectra. Encapsulant E can beselectively filled to any suitable level within the space disposedbetween one or more inner walls of retention material 132. For example,encapsulant E can be filled to a level equal to the height of retentionmaterial 132 or to any level above or below the retention material. Thelevel of encapsulant E can be planar or curved in any suitable manner,such as concave or convex.

As discussed above, at least a portion of the top surface of body 112can be lapped, polished, coated, or otherwise modified to diminish therough, porous surface profile that is common to ceramics. Specifically,as shown in FIG. 3A, a top surface 112′ of body 112 can be improved bylapping, polishing, or other mechanical modification. Alternatively, asshown in FIG. 3B, a coating 119 that does not significantly reducereflection but has good surface morphology and thermal conductance canbe applied to top surface 112′. As shown in FIG. 3B, coating 119 canmerge with fillet 134 and be composed of the same materials (e.g.,silicone, epoxy), or coating 119 can alternatively be a separate elementand can have a different composition than fillet 134. Regardless of thespecific configuration, the improvement of top surface 112′ can providegreater adhesion and better thermal contact with the one or more LEDchips 114.

LED component 110 can also comprise a reflective layer 113 that can, forexample and without limitation, be positioned and disposed within body112 as shown in FIG. 3A. In another aspect, reflective layer 113′ can asshown in FIG. 3A in broken lines optionally instead only be positionedand disposed on a bottom surface of body 112 (i.e., a surface opposingthe top surface on which one or more LED chips 114 are disposed).Reflective layers 113 or 113′ can, for example, comprise a metalreflector (e.g., a silver layer), a white thermal compound, or any othermaterial known to limit loss through the bottom surface of body 112,thereby further improving total reflection of LED component 110.Reflective layers 113 or 113′ can comprise metal or a dielectricmaterial and can for example be two ceramic or other reflectivematerials bonded together. Much of the light not initially reflected bythe highly reflective body 112 can be transmitted to a different surfaceof body 112 (e.g., a back or bottom surface), so reflective layers 113or 113′ can further advantageously assist in recovery of such light forexample.

Furthermore, additional material layers can be provided in combinationwith body 112 to define a multi-layer substrate. As shown in FIG. 3B,for example, at least one additional substrate layer 115 can be providedin combination with body 112. In this configuration, the combination ofmaterial layers can define a gradient in which body 112 can comprise acomparatively denser layer with optimized thermal conductivity (e.g., asapphire layer), whereas substrate layer 115 can exhibit comparativelyimproved reflection. In this regard, substrate layer 115 can have acomparatively higher degree of porosity with respect to body 112 suchthat substrate layer 115 exhibits a higher degree of diffusereflectivity. For example, the degree of porosity in substrate layer 115can be approximately equal to or greater than approximately twice thedegree of porosity in body 112. This configuration can allow heat todissipate away from the die while still producing a high degree of totalreflection.

In some aspects, light produced by LED chip 114 can penetrate fartherinto the multi-layer substructure before being reflected back into theepi-layers that can re-absorb the light. This configuration can alsocomprise a reflective layer 113 that can, for example and withoutlimitation, be positioned and disposed within body 112. In anotheraspect, reflective layer 113′ can as shown in broken lines in FIG. 3Boptionally instead only be positioned and disposed on a bottom surfaceof substrate layer 115. Reflective layers 113 or 113′ can for examplecomprise a metal reflector (e.g., a silver layer), a white thermalcompound, or any other material known to limit loss, thereby furtherimproving total reflection of LED component 110. Reflective layers 113or 113′ can comprise metal or a dielectric material and can for examplebe two ceramic or other reflective materials bonded together.

Referring now to FIGS. 4 to 6B, further alternative configurations for alight emitter device component comprising a ceramic-based LEDconfiguration such as those discussed above can incorporate a recessthat can be defined by walls forming an opening. FIGS. 4 and 5illustrate a light emitter package or LED component, generallydesignated 140, comprising a package body 141 formed by outer walls 142,143, 144, and 145. Package body 141 can comprise any material known inthe art. For example, body 141 can comprise molded plastic, ceramic,thermoset, silicone and/or thermoplastic materials or any combination ofthese or other materials. Similarly to the configurations describedabove, body 141 can comprise a ceramic body cast using low temperatureco-fired ceramic (LTCC) materials and processes, or HTCC can be used.

Outer walls 142 to 145 of LED component 140 can, for example only andwithout limitation, form a substantially square body 141. The shape canalso be any other shape or configuration, such as a rounded shape orconfiguration. Outer walls 142 to 145 can comprise one or more notches Nat the corners of body 141. LED component 140 can comprise a top surface146 and a bottom surface 148. One corner of LED component 140 cancomprise a mark 150 for identifying electrical characteristics for aparticular side of LED component 140. For example, mark 150 candesignate the side of the component comprising the anode or cathode.

LED component 140 can further comprise one or more inner walls defininga recess generally designated R. Here, inner walls 152, 153, 154, and155 define recess R within body 141. Inner walls 152 to 155 can comprisesubstantially squared or rounded corners where the inner walls meet.Optionally, component 140 may comprise a single inner wall defining asubstantially circular recess therein. Optionally, inner walls 152 to155 can be coated with a reflective material, such as silver, to furtherincrease the amount of light extracted per LED component 140.

One or more light emitters such as LEDs or LED chips 158 can mount to orbe disposed above lower surface 156. An LED chip 158 can mount upon oneor more intervening layers as shown for example in FIG. 6A, oralternatively an LED chip can mount directly upon lower surface 156without any intervening layer or layers as shown for example in FIG. 6B.Lower surface 156 of LED component 140 can comprise a first electricalcomponent 162 and a second electrical component 164 separated from lowersurface 156 by first and second non-metallic layers 163 and 165,respectively. First and second electrical components 162 and 164 caneach comprise a conductive material (e.g., silver metal) that is coupledto but physically separated from lower surface 156 by first and secondnon-metallic layers 163 and 165, respectively. The one or more LED chips158 can electrically connect to first and second electrical components162 and 164 using conductive wires 160 formed using a wirebondingprocess. One of the first and second electrical components 162 and 164serves as a cathode and the other as an anode for supplying the LEDchips 158 with current to illuminate an active layer within the LEDchip. Alternatively, the LED chips 158 may be flip-chip bonded to thefirst and second electrical components. Any other suitable bondingtechniques could be used as well.

LED component 140 can further comprise a thermal component 166. Thermalcomponent 166 can assist with managing thermal properties of LEDcomponent 140 by spreading and conducting heat away from the one or moreLED chips 158. In particular, as discussed above, thermal component 166can be a coating of material that improves the thermal contact and theability of LED chips 158 to be adhered to body 141. Thermal component166 can comprise one or more additional layers 168 to further improveheat spreading and thermal management capabilities of LED component 140.For example, additional layers 168 can comprise a die-attach layer.Using HTCC or any other suitable thermally conducting substrate mayreduce any need to use added thermal components.

Referring now to the cross-sectional view of FIG. 6A, taken along line6-6 of FIG. 4, features of LED component 140 are further illustrated. Inthis view recess R is defined by inner and outer walls 152, 154, 142,and 144, respectively. The opening of recess R can be as large aspossible without extending all the way to the edge of the outer walls142 and 144. Encapsulant E can be disposed within the recess, and cancontain one or more phosphors such that light emitted from the one ormore LED chips 158 produces an emission of desired output spectra.Encapsulant E, with or without phosphor included or later added, can befilled to any level within recess R, for example, flush with the topsurface 146 of LED component 140.

One or more LED chips 158 can electrically connect to first and secondelectrical components 162 and 164, respectively, by wirebonding usingelectrically conductive wire 160. LED chips 158 can mount within recessR upon one or more thermal components 166 comprising one or moreadditional thermally conductive layers 168. One or more interveninglayers such as, for example, conductive layer 168, can then be depositedby any suitable technique upon the thermal components.

At least one thermally conductive via 170 can be disposed, or buried,within body 141 and further disposed between thermal component 166 and athermal pad 172 extending from bottom surface 148 of LED component 140.Thermal pad 172 can further spread the heat dissipated from LEDcomponent 140 and can conduct the heat into an external heat sink.Thermal pad 172 can comprise any suitable shape, size, and/or geometryknown in the art. In one aspect, multiple conductive thermal vias 170can be used to dissipate the heat released from the one or more LEDchips 158. Conductive thermal vias 170 can conduct heat away from LEDcomponent 140 by causing heat to flow on a path out from the one or moreLED chips 158, into thermal element 166 and any intervening layers, suchas conductive layer 168, through body 141, out from thermal pad 172, andinto an external heat sink (not shown). The external heat sink cancomprise a printed circuit board (PCB) or other external element upon towhich the LED component 140 may thermally and electrically connect.Conductive thermal vias 170 can comprise any thermally conductivematerial known in the art, for example silver metal, which can assist inminimizing junction temperature difference between the LED chip(s) andthe external sink, thus prolonging the life of LED component 140.

As shown for example and without limitation in FIG. 6B, one or more LEDchip 158 can mount within recess R directly upon lower surface 156without any intervening layer. As one example, LED chip 158 can bemounted directly upon lower surface 156 without an intervening layer orstructure such as thermal component 166 or a conductive layer 168. Insuch a configuration, lower surface 156 can be lapped, polished, coated,or otherwise modified as discussed above to improve the thermal contactand/or adhesion strength for any components attached thereto. LEDcomponent 140 shown in FIG. 6B can but does not have to comprise aconductive thermal via 170 or thermal pad 172 or a protruding layer 174shown in FIG. 6A. Otherwise, LED component 140 as shown in FIG. 6B cancomprise identical features and structures to the embodiment shown inFIG. 6A.

Embodiments of the present disclosure shown in the drawings anddescribed above are exemplary of numerous embodiments that can be madewithin the scope of the appended claims. It is contemplated that theconfigurations of LED components such as those disclosed herein cancomprise numerous configurations other than those specificallydisclosed.

What is claimed is:
 1. A light emitter device component comprising: asubstrate comprising a ceramic material layer having a porosity ofgreater than 0% but less than approximately 15%, the porosity of thesubstrate being configured to produce a total reflection of visiblelight of greater than 95%, wherein a top surface of the ceramic materiallayer is disposed along a single plane, at least a portion of the topsurface of the ceramic material layer having been modified by lapping,polishing, and/or another mechanical modification to have a reducedporosity compared to an as-fired ceramic body; one or more light emitterdevices mounted on the portion of the top surface; and one or moreelectrical components mounted on the portion of the top surface by oneor more non-metallic adhesive layers and electrically coupled to the oneor more light emitter devices.
 2. The light emitter device componentaccording to claim 1, wherein the substrate comprises a thick-filmceramic substrate.
 3. The light emitter device component according toclaim 1, wherein the substrate comprises a thin-film ceramic substrate.4. The light emitter device component according to claim 1, wherein theportion of the top surface has a reduced porosity, and a remainder ofthe top surface has an unmodified porosity.
 5. The light emitter devicecomponent according to claim 4, wherein the portion of the top surfacehas a porosity that is approximately equal to or less than approximatelyhalf of a porosity of the remainder of the top surface.
 6. The lightemitter device component according to claim 1, wherein substantially allof the top surface has a reduced porosity compared to an as-firedceramic body.
 7. The light emitter device component according to claim1, wherein the substrate comprises a bottom surface opposing the topsurface, at least a portion of the bottom surface having a reducedporosity compared to an as-fired ceramic body.
 8. A method of forming alight emitter device component having increased brightness, the methodcomprising: mechanically modifying at least a portion of a top surfaceof a substrate comprising a ceramic material layer having a porosity ofgreater than 0% but less than approximately 15%, the top surface of thesubstrate being disposed along a single plane, the porosity of thesubstrate being configured to produce a total reflection of visiblelight of greater than 95%, wherein mechanically modifying at least aportion of the substrate comprises lapping, polishing, and/or anothermechanical modification such that the top surface of the ceramicmaterial layer has a reduced porosity compared to an as-fired ceramicbody; mounting one or more light emitter devices on the portion of thetop surface that is modified; providing one or more non-metallicadhesive layers on the top surface of the substrate; and mounting one ormore electrical components to the one or more non-metallic adhesivelayers.
 9. The method of claim 8, wherein the ceramic material layercomprises a thick-film ceramic material layer.
 10. The method of claim8, wherein the ceramic material layer comprises a thin-film ceramicmaterial layer.
 11. The method of claim 8, comprising modifyingsubstantially all of the top surface of the ceramic material layer tohave a reduced porosity compared to an as-fired ceramic body.
 12. Themethod of claim 8, comprising modifying at least a portion of a bottomsurface opposing the top surface of the ceramic material layer to have areduced porosity compared to an as-fired ceramic body.
 13. The method ofclaim 8, wherein the one or more electrical components are spaced fromthe substrate by the one or more non-metallic layers.